A photoresist composition to be used for semiconductor usually comprises a salt as an acid generator.
US2007/0122750A mentions a salt represented by the following formula as an acid generator.
(wherein X represents monocyclic or polycyclic hydrocarbon group having 3 to 30 carbon atoms or the like, Q1 and Q2 each independently represent a fluorine atom or a C1-C6 perfluoroalkyl group, and A+ represents an organic cation).